750W Shengyi direct drive hub motor vs 750W Bafang Geared Hub Motor

[Bill from MN]

Shengyi with 40 Nm of Tork vs. Bafang with 80 Nm of Tork.
On a 65lb ebike with a 7 speed derailer.
I am a 64 year old at 6'2" and 235 lbs. with weak knees
Is the Shengyi's 40 Nm of Tork enough to get me up hills with some pedaling on my part?
Or, is the Bafang's 80 Nm of Tork the only way to go?

 

[Alex M]

I recall 750W Bafang motor test results where they measured only 43 Nm.
So, in the end there might not be much difference.

 

[ElevenAD]

if you have bad knees the bafang geared hub is a better choice and even it is not great for climbing. something with a bafang mid drive will be real easy on your knees!

 

[Gene02638]

Shengyi with 40 Nm of Tork vs. Bafang with 80 Nm of Tork.
On a 65lb ebike with a 7 speed derailer.
I am a 64 year old at 6'2" and 235 lbs. with weak knees
Is the Shengyi's 40 Nm of Tork enough to get me up hills with some pedaling on my part?
Or, is the Bafang's 80 Nm of Tork the only way to go?

In regards to the direct drive motor, the voltage you are running is critical. 36 volts will max out at 20mph or so unassisted and will need some pedalling with most any hills. 48 volts will do around 30 mph unassisted and can be quite capable up most hills with assistance optional. A lot depends upon how steep and frequent your hills are.

 

[AHicks]

Shengyi with 40 Nm of Tork vs. Bafang with 80 Nm of Tork.
On a 65lb ebike with a 7 speed derailer.
I am a 64 year old at 6'2" and 235 lbs. with weak knees
Is the Shengyi's 40 Nm of Tork enough to get me up hills with some pedaling on my part?
Or, is the Bafang's 80 Nm of Tork the only way to go?

Bill, there's a lot to this question. The first thing I would want to know is are these both geared hubs, or is one of them a direct drive? The geared hubs have a huge advantage (5:1 gearing) over the direct drive when it comes to hills.

Second, your hills and my hills may be really different!

And last, Bafang has several motors that have been called 750 watt motors by different bike manf's. Just one of them is rated at 80nm I believe, the rest are less.

I'm a pretty active 69, and 6'2"/315 lbs. Our winter home is smack dab in the middle of a rolling coastal area with some pretty significant hills surrounding us. After a couple of direct drive motors (one 750 w the other 1500w), I am now completely spoiled by an aftermarket MAC 12t geared hub conservatively rated at 1000w and 100+nm.

My point is, this old man is going to go for the biggest gear driven rear hub he can get his hands on every time. My understanding is the 80nm Bafang is the REAL 750w motor, and it's pretty capable when coupled with a controller rated at 20-25amps. -Al

 

[Bill from MN]

The motors I am referring to are on the
Rad Power; RadCity Step-Thru 3 with the 750W Shengyi Direct Drive Hub Motor which they say has 40 Nm of tork
The second is the Rad Power ; Rad Rover 5 which they state as ; 750W brushless Bafang geared hub motor with 80 Nm of torque
There are some comments that the BaFang is a Rad City branded motor that is not the equal to the OEM BaFang you can get directly from BaFang
I love the RadCity Step-Thru 3, but their Direct Drive motor just does not seem to have enough Nm of tork to get me up the hills with only moderate pedaling
Rad City does not state the amp output of either controller

 

[AHicks]

Bill,
RAD controller output is pretty low. I'm thinking 12 amps continuous. More on that in a second. I don't remember them advertising the Rover motors as 80nm previously, so they may have changed recently. I would want to know for sure, but not sure how/what to ask them to get a straight answer.

Previously, RAD was installing a 350 watt motor in the Rovers and claiming it would handle 750 watts on a short term basis - which it did do. The hitch was the fact it was way down on torque when compared to a "real" 750 watt motor. Check out this video. It's not done by some crackpot. The info here has all been confirmed and well known among those that have researched it.

The same guy that did that video offers a reasonably priced, straight plug and play "kit" that replaces the stock Rad controller and display with a much better combo, capable of doing a much nicer job of delivering power from the battery to the motor. Folks are pretty happy with them. I did something similar using nearly the same components he uses, before his kits became available. I'm a big fan of this conversion....

All that said, MANY folks are very happy with their Rovers (and RAD City's) as-is. That's one of the reasons RAD sells so many of them. The other is RAD tends to bend over backwards to keep customers happy. -Al

 

[Alex M]

I'm not sure that RAD are branding Bafang hubs with their own name.
For a heavy rider I would prefer a 750W "nominal" geared rather than 750W "nominal" DD. Especially when terrain is not perfectly flat.

 

[mscir]

Shengyi with 40 Nm of Tork vs. Bafang with 80 Nm of Tork.
On a 65lb ebike with a 7 speed derailer.
I am a 64 year old at 6'2" and 235 lbs. with weak knees
Is the Shengyi's 40 Nm of Tork enough to get me up hills with some pedaling on my part?
Or, is the Bafang's 80 Nm of Tork the only way to go?

Did you buy a motor yet? I'd like to hear your opinion if you did. If not you may find this interesting.
Small Geared Hub Motor Showdown, Bafang G311/G310 vs Shengyi SX1/SX2

 

[AHicks]

What did you mean by "previously" Rad was using a 350W motor?
Did they switch to "Real 750W" motor recently?

Are you splitting hairs or is that a real question?